Group By：Spring JPA规格

我正在尝试使用Spring Data JPA规范，并想知道如何在规范中使用Group By 。 请参阅下面我当前的规格：

知识库

 public interface OauthAccessTokenRepository extends JpaRepository, JpaSpecificationExecutor { } 

规格

  public class OauthAccessTokenSpecification { public static Specification equalsTokenId(final String tokenId) { return new Specification() { public Predicate toPredicate(Root root,CriteriaQuery query, CriteriaBuilder cb) { return cb.equal(root.get("tokenId"), tokenId); } }; } public static Specification equalsRefreshToken(final String refreshToken) { return new Specification() { public Predicate toPredicate(Root root,CriteriaQuery query, CriteriaBuilder cb) { return cb.equal(root.get("refreshToken"), refreshToken); } }; } public static Specification equalsAuthenticationId(final String authenticationId) { return new Specification() { public Predicate toPredicate(Root root,CriteriaQuery query, CriteriaBuilder cb) { return cb.equal(root.get("authenticationId"), authenticationId); } }; } public static Specification equalsClientId(final String clientId) { return new Specification() { public Predicate toPredicate(Root root,CriteriaQuery query, CriteriaBuilder cb) { return cb.equal(root.get("clientId"), clientId); } }; } public static Specification equalsUserName(final String userName) { return new Specification() { public Predicate toPredicate(Root root,CriteriaQuery query, CriteriaBuilder cb) { return cb.equal(root.get("userName"), userName); } }; } }